import Vue from 'vue';
 
/** 拖拽 */
Vue.directive('dialogDrag', {
  bind(el, binding, vnode, oldVnode) {
    if (!binding.value) {
      return
    }
    const dialogHeaderEl = el.querySelector('.el-dialog__header');
    const dragDom = el.querySelector('.el-dialog');
    dialogHeaderEl.style.cssText += ';cursor:move;'
    dragDom.style.cssText += ';top:0px;'
    drag(dialogHeaderEl, dragDom)
  }
})
 
/** 最大化(支持拖拽) */
Vue.directive('dialogEnlarge', {
  bind(el, binding, vnode, oldVnode) {
    const attrs = vnode.data.attrs
    if (!binding.value.value) {
      return
    }
    let resizeEvent = new CustomEvent('drag-resize', {
      detail: '尺寸变化',
      bubbles: false
    });
    //初始化不最大化
    el.fullscreen = false;
    //弹框可拉伸最小宽高
    let minWidth = 400;
    let minHeight = 300;
    //当前宽高
    let nowWidth = minWidth;
    let nowHight = minHeight;
    //当前顶部高度
    let nowMarginTop = 0;
    //获取弹框头部（这部分可双击全屏）
    const dialogHeaderEl = el.querySelector('.el-dialog__header');
    //弹窗
    const dragDom = el.querySelector('.el-dialog');
    dragDom.className += ' el-drag-dialog';
    //清除选择头部文字效果
    dialogHeaderEl.onselectstart = new Function("return false");
    //头部加上可拖动cursor
    if (attrs.drag) {
      dialogHeaderEl.style.cursor = 'move';
      dialogHeaderEl.style.cssText += ';cursor:move;'
      dragDom.style.cssText += ';top:0px;'
      drag(dialogHeaderEl, dragDom)
    }
 
    //头部插入最大化最小化元素
    let maxMin = document.createElement("button");
    maxMin.className += ' el-dialog__headerbtn el-dialog__minmax';
    maxMin.style.right = '40px';
    maxMin.style.color = '#fff';
    maxMin.title = el.fullscreen ? '还原' : '最大化';
    maxMin.innerHTML = '<i class=' + (el.fullscreen ? '"el-icon-crop"' : '"el-icon-full-screen"') + ' onMouseOver="this.style.color=\'#909399\'" onMouseOut="this.style.color=\'#fff\'"></i>';
    dialogHeaderEl.insertBefore(maxMin, dialogHeaderEl.childNodes[1]);
    let bodyHeight = 'auto';
 
    function setMaxMin() {
      if (el.fullscreen) {
        let i = maxMin.querySelector('.el-icon-crop');
        i.classList.remove('el-icon-crop');
        i.classList.add('el-icon-full-screen');
        maxMin.innerHTML = '<i class="el-icon-full-screen"></i>';
        maxMin.title = '最大化';
        dragDom.style.height = "auto";
        dragDom.style.width = nowWidth + 'px';
        dragDom.style.margin = '10vh auto 50px';
        el.fullscreen = false;
        if (attrs.drag) {
          dialogHeaderEl.style.cursor = 'move';
          dialogHeaderEl.style.cssText += ';cursor:move;'
          dragDom.style.cssText += ';top:0px;'
          drag(dialogHeaderEl, dragDom)
        }
        dragDom.querySelector('.el-dialog__body').style.height = bodyHeight;
        dragDom.querySelector('.el-dialog__body').style['max-height'] = '55vh';
      } else {
        let i = maxMin.querySelector('.el-icon-full-screen');
        i.classList.remove('el-icon-full-screen');
        i.classList.add('el-icon-crop');
        maxMin.title = '还原';
        bodyHeight = dragDom.querySelector('.el-dialog__body').offsetHeight + 'px';
        nowHight = dragDom.clientHeight;
        nowWidth = dragDom.clientWidth;
        nowMarginTop = dragDom.style.marginTop;
        dragDom.style.left = 0;
        dragDom.style.top = 0;
        dragDom.style.height = "100%";
        dragDom.style.width = "100%";
        dragDom.style.margin = 0;
        dragDom.querySelector('.el-dialog__body').style.height = '100vh';
        dragDom.querySelector('.el-dialog__body').style['max-height'] = 'none';
        el.fullscreen = true;
        dialogHeaderEl.style.cursor = 'initial';
        dialogHeaderEl.onmousedown = null;
      }
      el.dispatchEvent(resizeEvent);
      binding.value.get(el.fullscreen)
    }
 
    //点击放大缩小效果
    maxMin.onclick = setMaxMin;
    //双击头部效果
    dialogHeaderEl.ondblclick = setMaxMin;
  }
})
 
 
/** 拖拽方法 */
function drag(el, dragDom) {
  // 获取原有属性 ie dom元素.currentStyle 火狐谷歌 window.getComputedStyle(dom元素, null);
  const sty = (function () {
    if (window.document.currentStyle) {
      return (dom, attr) => dom.currentStyle[attr];
    } else {
      return (dom, attr) => getComputedStyle(dom, false)[attr];
    }
  })()
 
  el.onmousedown = (e) => {
    // 鼠标按下，计算当前元素距离可视区的距离
    const disX = e.clientX - el.offsetLeft;
    const disY = e.clientY - el.offsetTop;
 
    const screenWidth = document.body.clientWidth; // body当前宽度
    const screenHeight = document.documentElement.clientHeight; // 可见区域高度(应为body高度，可某些环境下无法获取) 
 
    const dragDomWidth = dragDom.offsetWidth; // 对话框宽度
    const dragDomheight = dragDom.offsetHeight; // 对话框高度
 
    const minDragDomLeft = dragDom.offsetLeft;
    const maxDragDomLeft = screenWidth - dragDom.offsetLeft - dragDomWidth;
 
    const minDragDomTop = dragDom.offsetTop;
    const maxDragDomTop = screenHeight - dragDom.offsetTop - dragDomheight;
 
 
    // 获取到的值带px 正则匹配替换
    let styL = sty(dragDom, 'left');
    let styT = sty(dragDom, 'top');
 
    // 注意在ie中 第一次获取到的值为组件自带50% 移动之后赋值为px
    if (styL.includes('%')) {
      styL = +document.body.clientWidth * (+styL.replace(/\%/g, '') / 100);
      styT = +document.body.clientHeight * (+styT.replace(/\%/g, '') / 100);
    } else {
      styL = +styL.replace(/\px/g, '');
      styT = +styT.replace(/\px/g, '');
    };
 
    document.onmousemove = function (e) {
      // 通过事件委托，计算移动的距离 
      let left = e.clientX - disX;
      let top = e.clientY - disY;
 
      // 边界处理
      if (-(left) > minDragDomLeft) {
        left = -(minDragDomLeft);
      } else if (left > maxDragDomLeft) {
        left = maxDragDomLeft;
      }
 
      if (-(top) > minDragDomTop) {
        top = -(minDragDomTop);
      } else if (top > maxDragDomTop) {
        top = maxDragDomTop;
      }
 
      // 移动当前元素
      dragDom.style.cssText += `;left:${left + styL}px;top:${top + styT}px;`;
    };
 
    document.onmouseup = function (e) {
      document.onmousemove = null;
      document.onmouseup = null;
    };
  }
}